Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A method for forwarding a packet in a stacking system, wherein the stacking system comprises a core backbone (CB) device and a port extender (PE) device connected to the CB device, the method comprising: receiving, by a switch module of the CB device, a first packet sent from another device through a stacking port; wherein the stacking port is a first-level stacking port connecting the CB device with a neighbor CB device, or a second-level stacking port connecting the CB device with the PE device; in response to determining, based on source port information carried in the first packet, that the first packet enters the stacking system from the PE device and the first packet is a non-unicast packet, performing mirroring processing to the first packet to obtain a mirrored packet, and transmitting the first packet and the mirrored packet to a packet buffering module of the CB device; wherein the mirroring processing is associated with the first-level stacking port of the CB device; receiving a second packet sent from the packet buffering module; and in response to determining, based on source port information carried in the second packet a port at which the second packet entered the CB device, the port indicating that the second packet entered the stacking system from the PE device and the second packet is the first packet, forbidding forwarding of the second packet through all first-level stacking ports of the CB device.
A method for forwarding packets in a network stacking system comprised of a core backbone (CB) device and a port extender (PE) device. The CB device receives a packet from another device through a stacking port, which could be connected to another CB device or a PE device. If the packet originated from a PE device and is a non-unicast (e.g., broadcast, multicast) packet, the CB device duplicates the packet, creating a mirrored packet, and sends both the original and mirrored packets to a buffering module. The mirroring process is related to a CB device connection to another CB device. Later, if the CB device receives a packet from the buffering module that originated from the PE device and is the original non-unicast packet, the CB device will not forward that packet through any connections to other CB devices.
2. The method of claim 1 , further comprising: in response to determining, based on the source port information carried in the second packet, the port at which the second packet entered the CB device, the port indicating that the second packet enters the stacking system from the PE device and the second packet is the mirrored packet, forwarding the second packet through another first-level stacking port associated with the second packet.
In the packet forwarding method described previously, if the CB device receives a packet from the buffering module that originated from a PE device and is the *mirrored* non-unicast packet, the CB device *will* forward that mirrored packet through a CB device connection different from the one where the original packet came in. This ensures the mirrored packet traverses a different path in the stacking system.
3. The method of claim 1 , wherein the operation of performing the mirroring processing to the first packet comprises: when the first packet is received through the second-level stacking port, performing the mirroring processing to the first packet for each first-level stackingport of the CB device; when the first packet is received through the first-level stacking port, performing the mirroring processing to the first packet for another first-level stacking port of the CB device; and when the first packet is blocked at a stacking link between the neighbor CB device and the CB device connected to the neighbor CB device through the first-level stacking port, forbidding performing the mirroring processing to the first packet for the first-level stacking port.
In the packet forwarding method described previously, if the non-unicast packet from the PE device arrives at the CB device via a direct PE connection, the mirroring process duplicates the packet for *every* connection the CB device has to other CB devices. However, if the non-unicast packet arrives from another CB device connection, the mirroring process only duplicates the packet for the *other* CB device connections. Furthermore, if a connection to another CB device is blocked, mirroring to that specific connection is skipped, preventing forwarding to a blocked destination.
4. The method of claim 3 , further comprising: blocking non-unicast packets that enter the stacking system from different PE devices at different stacking links.
In the packet forwarding method where mirroring and non-forwarding rules are applied to non-unicast packets originating from PE devices, the system also blocks non-unicast packets entering from *different* PE devices at different stacking links. This prevents non-unicast traffic originating from different PE devices from flooding the entire stacked system by restricting their forwarding paths.
5. The method of claim 1 , further comprising: in response to determining, based on the source port information carried in the first packet, that the first packet enters the stacking system from another CB device and the first packet is the non-unicast packet, determining whether the stacking port receiving the first packet is the first-level stacking port on the CB device through which the CB device is connected to the other CB device via a shortest forwarding path; in response to determining that the stacking port receiving the first packet is the first-level stacking port through which the CB device is connected to the other CB device via the shortest forwarding path, transmitting the first packet to the packet buffering module; otherwise, discarding the first packet; in response to determining that the first packet enters the stacking system from the other CB device and the first packet is a unicast packet, transmitting the first packet to the packet buffering module; and in response to determining, based on the source port information carried in the second packet, that the second packet enters the stacking system from the other CB device, determining, based on the source port information carried in the second packet, the first-level stacking port on the CB device receiving the second packet, and forbidding forwarding the second packet through the determined first-level stacking port.
In the packet forwarding method described previously, if the first packet received by the CB device is a non-unicast packet that originated from *another* CB device, the system checks if the receiving connection is the "shortest path" to that other CB device. If it is the shortest path, the packet is sent to the buffering module. If it's not the shortest path, the packet is discarded. If the first packet originating from the other CB device is a *unicast* packet, it's always sent to the buffering module. Finally, when processing a packet from the buffering module that originated from another CB device, forwarding of that packet is blocked through the *same* connection it was originally received on, preventing loops.
6. The method of claim 5 , wherein when there are at least two equivalent forwarding paths between the CB device and the other CB device, the shortest forwarding path is selected from the at least two equivalent forwarding paths according to a predetermined path-selection rule; wherein the predetermined path-selection rule comprises: selecting, from the at least two equivalent forwarding paths, a forwarding path with minimum hops as the shortest forwarding path.
In the packet forwarding method from the previous description, where shortest paths are used for CB device to CB device communication, when multiple "shortest paths" exist, a predetermined rule selects one. This rule picks the path with the fewest "hops" (number of intermediate devices) as the preferred shortest path. This ensures consistent path selection and avoids potential routing oscillations or loops in the stacking system.
7. A device capable of acting as a core backbone (CB) device in a stacking system, the device comprising: a storage, to store machine-readable instructions; a processor, to execute the machine-readable instructions to: receive a first packet sent from another device through a stacking port; wherein the stacking port is a first-level stacking port to connect the CB device with a neighbor CB device, or a second-level stacking port to connect the CB device with a Port Extender (PE) device; in response to determining, based on source port information carried in the first packet, that the first packet entered the stacking system through the PE device and the first packet is a non-unicast packet, perform mirroring processing to the first packet to obtain a mirrored packet, and transmit the first packet and the mirrored packet to the CB device, wherein the mirroring processing is associated with the first-level stacking port of the CB device; receive a second packet sent from the CB device; and in response to determining, based on source port information carried in the second packet, a port at which the second packet entered the CB devices, the port indicating that the second packet entered the stacking system from the PE device and the second packet is the first packet, forbid forwarding the second packet through all first-level stacking ports of the CB device.
A network device designed to function as a core backbone (CB) device in a stacking system. It contains storage for instructions and a processor to execute those instructions. The device receives packets from stacking ports connected to other CB devices or PE devices. If a received packet originated from a PE device and is a non-unicast packet, the device duplicates the packet (mirrors it) and sends both the original and mirrored packets to a buffer. The mirroring process relates to CB device connections to other CB devices. Subsequently, if the device receives a packet from the buffer that originated from the PE device and is the original non-unicast packet, it will not forward the packet through any connections to other CB devices.
8. The device of claim 7 , wherein the processor is to execute the machine-readable instructions to: in response to determining, based on the source port information carried in the second packet, that the second packet entered the stacking system through the PE device and the second packet is the mirrored packet, forward the second packet through another first-level stacking port associated with the second packet.
The CB device described previously, when receiving a packet from the buffering module that originated from a PE device and is the *mirrored* non-unicast packet, the processor *will* forward that mirrored packet through a different CB device connection. This ensures the mirrored packet is sent along a different path in the network stacking system, providing redundancy or facilitating network monitoring.
9. The device of claim 7 , wherein the processor is to execute the machine-readable instructions to: when the first packet is received through the second-level stackingport, perform the mirroring processing to the first packet for each first-level stacking port of the CB device; when the first packet is received through the first-level stackingport, perform the mirroring processing to the first packet for another first-level stacking port of the CB device; and when the first packet is blocked at a stacking link between the neighbor CB device and the CB device connected to the neighbor CB device through the first-level stacking port, forbid performing the mirroring processing to the first packet for the first-level stacking port.
The CB device described previously executes instructions to handle mirroring based on packet source. If a non-unicast packet arrives from a PE device connection, mirroring duplicates it for *every* CB device connection. If it arrives from a CB device connection, it's only mirrored for the *other* CB device connections. If a connection to another CB device is blocked, mirroring to that specific connection is skipped.
10. The device of claim 9 , wherein the processor is to execute the machine-readable instructions to: block non-unicast packets that enter the stacking system from different PE devices at different stacking links.
The CB device described previously also implements blocking rules. Non-unicast packets entering the system from *different* PE devices are blocked at different stacking links. This prevents broadcast storms originating from multiple PE devices by restricting their propagation within the stacked system.
11. The device of claim 7 , wherein the processor is to execute the machine-readable instructions to: in response to determining, based on the source port information carried in the first packet, that the first packet enters the stacking system from another CB device and the first packet is the non-unicast packet, determine whether the stacking port receiving the first packet is the first-level stacking port on the CB device through which the CB device is connected to the other CB device via a shortest forwarding path; in response to determining that the stacking port receiving the first packet is the first-level stacking port through which the CB device is connected to the other CB device via the shortest forwarding path, transmit the first packet; otherwise, discard the first packet; in response to determining that the first packet enters the stacking system from the other CB device and the first packet is a unicast packet, transmit the first packet; and in response to determining, based on the source port information carried in the second packet, that the second packet entered the stacking system from the other CB device, determine, based on the source port information carried in the second packet, another first-level stacking port on the CB device receiving the second packet, and forbid forwarding the second packet through the determined first-level stacking port.
The CB device described previously handles non-unicast packets originating from *another* CB device by checking if the receiving connection is the "shortest path." If it is, the packet is transmitted. Otherwise, it's discarded. If the packet is a *unicast* packet from another CB device, it's always transmitted. When handling a packet from the buffer that originated from another CB device, the device blocks forwarding of that packet through the *same* connection it was originally received on.
12. The device of claim 11 , wherein when there are at least two equivalent forwarding paths between the CB device and the other CB device, the shortest forwarding path is selected from the at least two equivalent forwarding paths according to a predetermined path-selection rule; wherein the predetermined path-selection rule comprises: selecting, from the at least two equivalent forwarding paths, a forwarding path with minimum hops as the shortest forwarding path.
The CB device described previously uses shortest path routing. If multiple equal-cost paths exist between CB devices, a pre-defined rule selects the path with the fewest hops (intermediate devices). This provides consistent path selection, and simplifies routing logic, preventing routing loops.
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December 5, 2017
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